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Pulchinenoside B4, a natural saponin monomer from the Pulsatilla plant, plays an important role as an immunomodulator in the treatment of acute inflammation. Oral ulcer (OU) is a common ulcerative injury disease that occurs in the oral mucosa, including mucosal ulceration and abnormalities of lips and tongue. A close correlation exists between gut microbiota and circulating metabolites in patients with OU. However, the correlation between gut microbiota and serum metabolomics is not clear. Therefore, this study aimed to explore the changes in gut microbiota and metabolites in OU. The 16S ribosomal RNA (16S rRNA) gene sequencing was used to detect the changes in the composition of gut microbiota in OU rat model. Moreover, the endogenous small metabolites were explored by collecting the non-targeted serum metabolomics data. A total of 34 OU-related biomarkers were identified, mainly related to fatty acid metabolism and inflammatory pathways. The administration of B4 effectively reduced the occurrence of OU and restored the levels of multiple endogenous biomarkers and key gut microbial species to the normal level. This study demonstrated that the gut microbiota and metabolites were altered in the OU rat model, which were significantly restored to the normal level by B4, thereby showing good application prospects in the treatment of OU. Key points: • The first investigating the correlation between OU and gut microbiota. • A close correlation between metabolites and gut microbiota in OU disease was successfully identified. • Pulchinenoside B4 ameliorates oral ulcers in rats by modulating gut microbiota and metabolites. [ABSTRACT FROM AUTHOR]

The gastrointestinal tract (GIT) is stationed by a dynamic and complex microbial community with functions in digestion, metabolism, immunomodulation, and reproduction. However, there is relatively little research on the composition and function of microorganisms in different GIT segments in dairy goats. Herein, 80 chyme samples were taken from ten GIT sites of eight Xinong Saanen dairy goats and then analyzed and identified the microbial composition via 16S rRNA V1-V9 amplicon sequencing. A total of 6669 different operational taxonomic units (OTUs) were clustered, and 187 OTUs were shared by ten GIT segments. We observed 264 species belonging to 23 different phyla scattered across ten GITs, with Firmicutes (52.42%) and Bacteroidetes (22.88%) predominating. The results revealed obvious location differences in the composition, diversity, and function of the GIT microbiota. In LEfSe analysis, unidentified_Lachnospiraceae and unidentified_Succinniclassicum were significantly enriched in the four chambers of stomach, with functions in carbohydrate fermentation to compose short-chain fatty acids. Aeriscardovia, Candidatus_Saccharimonas, and Romboutsia were significantly higher in the foregut, playing an important role in synthesizing enzymes, amino acids, and vitamins and immunomodulation. Akkermansia, Bacteroides, and Alistipes were significantly abundant in the hindgut to degrade polysaccharides and oligosaccharides, etc. From rumen to rectum, α-diversity decreased first and then increased, while β-diversity showed the opposite trend. Metabolism was the major function of the GIT microbiome predicted by PICRUSt2, but with variation in target substrates along the regions. In summary, GIT segments play a decisive role in the composition and functions of microorganisms. Key points: • The jejunum and ileum were harsh for microorganisms to colonize due to the presence of bile acids, enzymes, faster chyme circulation, etc., exhibiting the lowest α-diversity and the highest β-diversity. • Variability in microbial profiles between the three foregut segments was greater than four chambers of stomach and hindgut, with a higher abundance of Firmicutes dominating than others. • Dairy goats dominated a higher abundance of Kiritimatiellaeota than cows, which was reported to be associated with fatty acid synthesis. [ABSTRACT FROM AUTHOR]

The African swine fever virus (ASFV) has the ability to infect pigs and cause a highly contagious acute fever that can result in a mortality rate as high as 100%. Due to the viral epidemic, the pig industry worldwide has suffered significant financial setbacks. The absence of a proven vaccine for ASFV necessitates the development of a sensitive and reliable serological diagnostic method, enabling laboratories to effectively and expeditiously detect ASFV infection. In this study, four strains of monoclonal antibodies (mAbs) against p72, namely, 5A1, 4C4, 8A9, and 5E10, were generated through recombinant expression of p72, the main capsid protein of ASFV, and immunized mice with it. Epitope localization was performed by truncated overlapping polypeptides. The results indicate that 5A1 and 4C4 recognized the amino acid 20–39 aa, 8A9 and 5E10 are recognized at 263–282 aa, which is consistent with the reported 265–280 aa epitopes. Conserved analysis revealed 20–39 aa is a high conservation of the epitopes in the ASFV genotypes. Moreover, a blocking ELISA assay for detection ASFV antibody based on 4C4 monoclonal antibody was developed and assessed. The receiver-operating characteristic (ROC) was performed to identify the best threshold value using 87 negative and 67 positive samples. The established test exhibited an area under the curve (AUC) of 0.9997, with a 95% confidence interval ranging from 99.87 to 100%. Furthermore, the test achieved a diagnostic sensitivity of 100% (with a 95% confidence interval of 95.72 to 100%) and a specificity of 98.51% (with a 95% confidence interval of 92.02 to 99.92%) when the threshold was set at 41.97%. The inter- and intra-batch coefficient of variation were below 10%, demonstrating the exceptional repeatability of the method. This method can detect the positive standard serum at a dilution as high as 1:512. Subsequently, an exceptional blocking ELISA assay was established with high diagnostic sensitivity and specificity, providing a novel tool for detecting ASFV antibodies. Key points: • Four strains of ASFV monoclonal antibodies against p72 were prepared and their epitopes were identified. • Blocking ELISA method was established based on monoclonal antibody 4C4 with an identified conservative epitope. • The established blocking ELISA method has a good effect on the detection of ASFV antibody. [ABSTRACT FROM AUTHOR]

Chemoautotrophic canonical ammonia oxidizers (ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB)) and complete ammonia oxidizers (comammox Nitrospira) are accountable for ammonia oxidation, which is a fundamental process of nitrification in terrestrial ecosystems. However, the relationship between autotrophic nitrification and the active nitrifying populations during 15N-urea incubation has not been totally clarified. The 15N-labeled DNA stable isotope probing (DNA-SIP) technique was utilized in order to study the response from the soil nitrification process and the active nitrifying populations, in both acidic and neutral paddy soils, to the application of urea. The presence of C2H2 almost completely inhibited NO3−-N production, indicating that autotrophic ammonia oxidation was dominant in both paddy soils. 15N-DNA-SIP technology could effectively distinguish active nitrifying populations in both soils. The active ammonia oxidation groups in both soils were significantly different, AOA (NS (Nitrososphaerales)-Alpha, NS-Gamma, NS-Beta, NS-Delta, NS-Zeta and NT (Ca. Nitrosotaleales)-Alpha), and AOB (Nitrosospira) were functionally active in the acidic paddy soil, whereas comammox Nitrospira clade A and Nitrosospira AOB were functionally active in the neutral paddy soil. This study highlights the effective discriminative effect of 15N-DNA-SIP and niche differentiation of nitrifying populations in these paddy soils. Key points: • 15N-DNA-SIP technology could effectively distinguish active ammonia oxidizers. • Comammox Nitrospira clade A plays a lesser role than canonical ammonia oxidizers. • The active groups in the acidic and neutral paddy soils were significantly different. [ABSTRACT FROM AUTHOR]

Enzyme immobilized on magnetic nanomaterials is a promising biocatalyst with efficient recovery under applied magnets. In this study, a recombinant extracellular lipase from Aspergillus niger GZUF36 (PEXANL1) expressed in Pichia pastoris GS115 was immobilized on ionic liquid-modified magnetic nano ferric oxide (Fe3O4@SiO2@ILs) via electrostatic and hydrophobic interaction. The morphology, structure, and properties of Fe3O4@SiO2@ILs and immobilized PEXANL1 were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, vibration sample magnetometer, and zeta potential analysis. Under optimized conditions, the immobilization efficiency and activity recovery of immobilized PEXANL1 were 52 ± 2% and 122 ± 2%, respectively. The enzymatic properties of immobilized PEXANL1 were also investigated. The results showed that immobilized PEXANL1 achieved the maximum activity at pH 5.0 and 45 °C, and the lipolytic activity of immobilized PEXANL1 was more than twice that of PEXANL1. Compared to PEXANL1, immobilized PEXANL1 exhibited enhanced tolerance to temperature, metal ions, surfactants, and organic solvents. The operation stability experiments revealed that immobilized PEXANL1 maintained 86 ± 3% of its activity after 6 reaction cycles. The enhanced catalytic performance in enzyme immobilization on Fe3O4@SiO2@ILs made nanobiocatalysts a compelling choice for bio-industrial applications. Furthermore, Fe3O4@SiO2@ILs could also benefit various industrial enzymes and their practical uses. Key points: • Immobilized PEXANL1 was confirmed by SEM, FT-IR, and XRD. • The specific activity of immobilized PEXANL1 was more than twice that of PEXANL1. • Immobilized PEXANL1 had improved properties with good operational stability. [ABSTRACT FROM AUTHOR]

Glucosylglycerol (GG) is a natural compatible solute that can be synthesized by many cyanobacteria and a few heterotrophic bacteria under high salinity conditions. In cyanobacteria, GG is synthesized by GG-phosphate synthase and GG-phosphate phosphatase, and a hydrolase GGHA catalyzes its degradation. In heterotrophic bacteria (such as some Marinobacter species), a fused form of GG-phosphate phosphatase and GG-phosphate synthase is present, but the cyanobacteria-like degradation pathway is not available. Instead, a phosphorylase GGP, of which the coding gene is located adjacent to the gene that encodes the GG-synthesizing enzyme, is supposed to perform the GG degradation function. In the present study, a GGP homolog from the salt-tolerant M. salinexigens ZYF650T was characterized. The recombinant GGP catalyzed GG decomposition via a two-step process of phosphorolysis and hydrolysis in vitro and exhibited high substrate specificity toward GG. The activity of GGP was enhanced by inorganic salts at low concentrations but significantly inhibited by increasing salt concentrations. While the investigation on the physiological role of GGP in M. salinexigens ZYF650T was limited due to the failed induction of GG production, the heterologous expression of ggp in the living cells of the GG-producing cyanobacterium Synechocystis sp. PCC 6803 significantly reduced the salt-induced GG accumulation. Together, these data suggested that GGP may represent a novel pathway of microbial GG catabolism. Key points: • GGP catalyzes GG degradation by a process of phosphorolysis and hydrolysis • GGP-catalyzed GG degradation is different from GGHA-based GG degradation • GGP represents a potential novel pathway of microbial GG catabolism [ABSTRACT FROM AUTHOR]

Diketopiperazine alkaloids have proven the most abundant heterocyclic alkaloids up to now, which usually process diverse scaffolds and rich biological activities. In our search for bioactive diketopiperazine alkaloids from marine-derived fungi, two novel diketopiperazine alkaloids, penipiperazine A (1) and its biogenetically related new metabolite (2), together with a known analogue neofipiperzine C (3), were obtained from the strain Penicillium brasilianum. Their planar structures and absolute configurations were elucidated by extensive spectroscopic analyses, 13C NMR calculation, Marfey's, ECD, and ORD methods. Compound 1 featured a unique 6/5/6/6/5 indole-pyrazino-pyrazino-pyrrolo system, and its plausible biogenetic pathway was also proposed. Additionally, compounds 1–3 have been tested for their inflammatory activities. 1 and 2 significantly inhibited the release of NO and the expression of related pro-inflammatory cytokines on LPS-stimulated RAW264.7 cells, suggesting they could be attracting candidate for further development as anti-inflammatory agent. Key points: • A novel diketopiperazine alkaloid featuring a unique 6/5/6/6/5 indole-pyrazino-pyrazino-pyrrolo system was isolated from the marine fungus Penicillium brasilianum. • The structure of 1 was elucidated by detailed analysis of 2D NMR data, 13C NMR calculation, Marfey's, ECD, and ORD methods. • Compounds 1 and 2 significantly inhibited the release of NO and the expression of related pro-inflammatory cytokines on LPS-stimulated RAW264.7 cells. [ABSTRACT FROM AUTHOR]

Aquaculture has suffered significant financial losses as a result of the infection of zoonotic Aeromonas hydrophila, which has a high level of resistance to classic antibiotics. In this study, we isolated an A. hydrophila strain B3 from diseased soft-shelled turtle (Pelodiscus sinensis), which is one of the most commercially significant freshwater farmed reptiles in East Asia, and found that A. hydrophila was its dominant pathogen. To better understand the inhibition effect and action mechanism of Chinese herbs on A. hydrophila, we conducted Chinese herbs screening and found that Lonicera japonica had a significant antibacterial effect on A. hydrophila B3. Experimental therapeutics of L. japonica on soft-shelled turtle showed that the supplement of 1% L. japonica to diet could significantly upregulate the immunity-related gene expression of soft-shelled turtle and protect soft-shelled turtle against A. hydrophila infection. Histopathological section results validated the protective effect of L. japonica. As the major effective component of L. japonica, chlorogenic acid demonstrated significant inhibitory effect on the growth of A. hydrophila with MIC at 6.4 mg/mL. The in vitro assay suggested that chlorogenic acid could inhibit the hemolysin/protease production and biofilm formation of A. hydrophila and significantly decrease the expression of quorum sensing, biofilm formation, and hemolysin-related genes in A. hydrophila. Our results showed that the Chinese herb L. japonica would be a promising candidate for the treatment of A. hydrophila infections in aquaculture, and it not only improves the immune response of aquatic animals but also inhibits the virulence factor (such as biofilm formation) expression of A. hydrophila. Key points: • A. hydrophila was the dominant pathogen of the diseased soft-shelled turtle. • L. japonica can protect soft-shelled turtle against A. hydrophila infection. • Chlorogenic acid inhibits the growth and biofilm formation of A. hydrophila. [ABSTRACT FROM AUTHOR]

The cellulose-rich corncob residue (CCR) is an abundant and renewable agricultural biomass that has been under-exploited. In this study, two strategies were compared for their ability to transform CCR into cello-oligosaccharides (COS). The first strategy employed the use of endo-glucanases. Although selected endo-glucanases from GH9, GH12, GH45, and GH131 could release COS with degrees of polymerization from 2 to 4, the degrading efficiency was low. For the second strategy, first, CCR was efficiently depolymerized to glucose and cellobiose using the cellulase from Trichoderma reesei. Then, using these simple sugars and sucrose as the starting materials, phosphorylases from different microorganisms were combined to generate COS to a level up to 100.3 g/L with different patterns and degrees of polymerization. Using tomato as a model plant, the representative COS obtained from BaSP (a sucrose phosphorylase from Bifidobacterium adolescens), CuCbP (a cellobiose phosphorylase from Cellulomonas uda), and CcCdP (a cellodextrin phosphorylase from Clostridium cellulosi) were shown to be able to promote plant growth. The current study pointed to an approach to make use of CCR for production of the value-added COS. Key points: • Sequential use of cellulase and phosphorylases effectively generated cello-oligosaccharides from corncob residue. • Cello-oligosaccharides patterns varied in accordance to cellobiose/cellodextrin phosphorylases. • Spraying cello-oligosaccharides promoted tomato growth. [ABSTRACT FROM AUTHOR]

Type 2 diabetes (T2D), a global health concern, is closely associated with the gut microbiota. Restoration of a balanced microbiota and intestinal homeostasis benefit therapy of T2D. Some special phages may selectively alter the gut microbiota without causing dysbiosis, such as MS2 and P22. However, scarcely systematic analysis of cascading effects triggered by MS2 and P22 phages on the microbiota, as well as interactions between specific gut bacteria and systemic metabolism, seriously inhibit the development of positive interventions of phages. Based on multi-omic analysis, we analyzed the intrinsic correlations among specific microbiota, their bioactive metabolites, and key indicators of T2D. We found that gavage of the MS2-P22 phage cocktail could significantly alter the gut microbiome to attenuate dysbiosis of diabetic C57BL/6 mice caused by high-fat diets (HFDs) and streptozotocin (STZ), by affecting microbial compositions as well as their metabolic pathways and metabolites, especially increasing amounts of short-chain fatty acid-producing (SCFA-producing) bacteria (e.g., Blautia and Romboutsia) and short-chain fatty acids (SCFAs). Correspondingly, a noteworthy reduction in the number of several opportunistic pathogens occurred, e.g., Candidatus Saccharimonas, Aerococcus, Oscillibacter, Desulfovibrio, and Clostridium sensu stricto 1. Synchronously, the levels of proinflammatory cytokines and lipopolysaccharide (LPS) were reduced to recover gut barrier function in T2D mice. These findings might benefit the development of a new dietary intervention for T2D based on phage cocktails. Key points: • Intestinal barrier integrity of T2D mice is improved by a phage cocktail • Negative relationship between Muribaculaceae and Corynebacterium reshaped gut microbiota • Acetate, propionate, and butyrate decreased the level of proinflammatory factors [ABSTRACT FROM AUTHOR]

Cyclophilin A (CypA), the first member of cyclophilins, is distributed extensively in eukaryotic and prokaryotic cells, primarily localized in the cytoplasm. In addition to acting as an intracellular receptor for cyclosporin A (CSA), CypA plays a crucial role in diseases such as aging and tumorigenesis. Apoptosis, a form of programmed cell death, is able to balance the rate of cell viability and death. In this review, we focus on the effects of CypA on apoptosis and the relationship between specific mechanisms of CypA promoting or inhibiting apoptosis and diseases, including tumorigenesis, cardiovascular diseases, organ injury, and microbial infections. Notably, the process of CypA promoting or inhibiting apoptosis is closely related to disease development. Finally, future prospects for the association of CypA and apoptosis are discussed, and a comprehensive understanding of the effects of CypA on apoptosis in relation to diseases is expected to provide new insights into the design of CypA as a therapeutic target for diseases. Key points: • Understand the effect of CypA on apoptosis. • CypA affects apoptosis through specific pathways. • The effect of CypA on apoptosis is associated with a variety of disease processes. [ABSTRACT FROM AUTHOR]

Three new strains of dissimilatory perchlorate-reducing bacteria (DPRB), QD19-16, QD1-5, and P3-1, were isolated from an active sludge. Phylogenetic trees based on 16S rRNA genes indicated that QD19-16, QD1-5, and P3-1 belonged to Brucella, Acidovorax, and Citrobacter, respectively, expanding the distribution of DPRB in the Proteobacteria. The three strains were gram-negative and facultative anaerobes with rod-shaped cells without flagella, which were 1.0–1.6 μm long and 0.5–0.6 μm wide. The three DPRB strains utilized similar broad spectrum of electron donors and acceptors and demonstrated a similar capability to reduce perchlorate within 6 days. The enzyme activity of perchlorate reductase in QD19-16 toward chlorate was higher than that toward perchlorate. The high sequence similarity of the perchlorate reductase operon and chlorite dismutase genes in the perchlorate reduction genomic islands (PRI) of the three strains implied that they were monophyletic origin from a common ancestral PRI. Two transposase genes (tnp1 and tnp2) were found in the PRIs of strain QD19-16 and QD1-5, but were absent in the strain P3-1 PRI. The presence of fragments of IR sequences in the P3-1 PRI suggested that P3-1 PRI had previously contained these two tnp genes. Therefore, it is plausible to suggest that a common ancestral PRI transferred across the strains Brucella sp. QD19-16, Acidovorax sp. QD1-5, and Citrobacter sp. P3-1 through horizontal gene transfer, facilitated by transposases. These results provided a direct evidence of horizontal gene transfer of PRI that could jump across phylogenetically unrelated bacteria through transposase. Key points: • Three new DPRB strains can effectively remove high concentration of perchlorate. • The PRIs of three DPRB strains are acquired from a single ancestral PRI. • PRIs are incorporated into different bacteria genome through HGT by transposase. [ABSTRACT FROM AUTHOR]

Type 2 diabetes (T2D), a global health concern, is closely associated with the gut microbiota. Restoration of a balanced microbiota and intestinal homeostasis benefit therapy of T2D. Some special phages may selectively alter the gut microbiota without causing dysbiosis, such as MS2 and P22. However, scarcely systematic analysis of cascading effects triggered by MS2 and P22 phages on the microbiota, as well as interactions between specific gut bacteria and systemic metabolism, seriously inhibit the development of positive interventions of phages. Based on multi-omic analysis, we analyzed the intrinsic correlations among specific microbiota, their bioactive metabolites, and key indicators of T2D. We found that gavage of the MS2-P22 phage cocktail could significantly alter the gut microbiome to attenuate dysbiosis of diabetic C57BL/6 mice caused by high-fat diets (HFDs) and streptozotocin (STZ), by affecting microbial compositions as well as their metabolic pathways and metabolites, especially increasing amounts of short-chain fatty acid-producing (SCFA-producing) bacteria (e.g., Blautia and Romboutsia) and short-chain fatty acids (SCFAs). Correspondingly, a noteworthy reduction in the number of several opportunistic pathogens occurred, e.g., Candidatus Saccharimonas, Aerococcus, Oscillibacter, Desulfovibrio, and Clostridium sensu stricto 1. Synchronously, the levels of proinflammatory cytokines and lipopolysaccharide (LPS) were reduced to recover gut barrier function in T2D mice. These findings might benefit the development of a new dietary intervention for T2D based on phage cocktails. Key points: • Intestinal barrier integrity of T2D mice is improved by a phage cocktail • Negative relationship between Muribaculaceae and Corynebacterium reshaped gut microbiota • Acetate, propionate, and butyrate decreased the level of proinflammatory factors [ABSTRACT FROM AUTHOR]

Cyclophilin A (CypA), the first member of cyclophilins, is distributed extensively in eukaryotic and prokaryotic cells, primarily localized in the cytoplasm. In addition to acting as an intracellular receptor for cyclosporin A (CSA), CypA plays a crucial role in diseases such as aging and tumorigenesis. Apoptosis, a form of programmed cell death, is able to balance the rate of cell viability and death. In this review, we focus on the effects of CypA on apoptosis and the relationship between specific mechanisms of CypA promoting or inhibiting apoptosis and diseases, including tumorigenesis, cardiovascular diseases, organ injury, and microbial infections. Notably, the process of CypA promoting or inhibiting apoptosis is closely related to disease development. Finally, future prospects for the association of CypA and apoptosis are discussed, and a comprehensive understanding of the effects of CypA on apoptosis in relation to diseases is expected to provide new insights into the design of CypA as a therapeutic target for diseases. Key points: • Understand the effect of CypA on apoptosis. • CypA affects apoptosis through specific pathways. • The effect of CypA on apoptosis is associated with a variety of disease processes. [ABSTRACT FROM AUTHOR]

Three new strains of dissimilatory perchlorate-reducing bacteria (DPRB), QD19-16, QD1-5, and P3-1, were isolated from an active sludge. Phylogenetic trees based on 16S rRNA genes indicated that QD19-16, QD1-5, and P3-1 belonged to Brucella, Acidovorax, and Citrobacter, respectively, expanding the distribution of DPRB in the Proteobacteria. The three strains were gram-negative and facultative anaerobes with rod-shaped cells without flagella, which were 1.0–1.6 μm long and 0.5–0.6 μm wide. The three DPRB strains utilized similar broad spectrum of electron donors and acceptors and demonstrated a similar capability to reduce perchlorate within 6 days. The enzyme activity of perchlorate reductase in QD19-16 toward chlorate was higher than that toward perchlorate. The high sequence similarity of the perchlorate reductase operon and chlorite dismutase genes in the perchlorate reduction genomic islands (PRI) of the three strains implied that they were monophyletic origin from a common ancestral PRI. Two transposase genes (tnp1 and tnp2) were found in the PRIs of strain QD19-16 and QD1-5, but were absent in the strain P3-1 PRI. The presence of fragments of IR sequences in the P3-1 PRI suggested that P3-1 PRI had previously contained these two tnp genes. Therefore, it is plausible to suggest that a common ancestral PRI transferred across the strains Brucella sp. QD19-16, Acidovorax sp. QD1-5, and Citrobacter sp. P3-1 through horizontal gene transfer, facilitated by transposases. These results provided a direct evidence of horizontal gene transfer of PRI that could jump across phylogenetically unrelated bacteria through transposase. Key points: • Three new DPRB strains can effectively remove high concentration of perchlorate. • The PRIs of three DPRB strains are acquired from a single ancestral PRI. • PRIs are incorporated into different bacteria genome through HGT by transposase. [ABSTRACT FROM AUTHOR]

Escherichia coli, a well-known prokaryotic organism, has been widely employed as a versatile host for heterologous overexpression of proteins/biocatalysts and the production of pharmaceutically important intermediates/small molecules. However, some E. coli endogenous enzymes showing substrate promiscuity may disturb the heterologous metabolic flux, which will result in the reduction of substrates, intermediates, and target products. Here we reported an unexpected E. coli-catalyzed regioselective O-acetylation of various glucosides. The regioselectively O-acetylated products, 6′-O-acetyl-loganin and 6′-O-acetyl-loganic acid, were obtained and characterized from the enzymatic reaction in which the supernatants of E. coli expressing either CaCYP72A565 and CaCPR, the key enzymes involved in camptothecin biosynthesis, or empty vector were used as catalyst and loganin and loganic acid as independent substrate. An alkaloidal glucoside strictosamide was converted into the regioselectively O-acetylated product 6′-O-acetyl-strictosamide, implying substrate promiscuity of the E. coli-catalyzed O-acetylation reaction. Furthermore, 8 glucosides, including 5 iridoid glucosides and 3 flavonoid glucosides, were successfully converted into the regioselectively O-acetylated products by E. coli, indicating the wide substrate range for the unexpected E. coli-catalyzed O-acetylation. E. coli maltose O-acetyltransferase was demonstrated to be responsible for the mentioned regioselective O-acetylation at the 6-OH of the glucopyranosyl group of multiple classes of natural product glucosides through candidate acetyltransferase-encoding gene analysis, gene knock-out, gene complementation, and the relevant enzymatic reaction activity assays. The present study not only provides an efficient biocatalyst for regioselective O-acetylation but also notifies cautions for metabolic engineering and synthetic biology applications in E. coli. Key points: • 6-OH of glucosyl of multiple glucosides was regioselectively O-acetylated by E. coli. • Endogenous EcMAT is responsible for the regioselective O-acetylation reaction. [ABSTRACT FROM AUTHOR]

Surfactin is a lipopeptide which has attracted massive attention due to its versatile bioactive properties, although it has less commercial application due to its low yield in wild strains. The B. velezensis Bs916 has enable commercial production of surfactin due to its outstanding capacity to synthesize lipopeptides and amenable to genetically engineering. In this study, 20 derivatives with high surfactin production were obtained firstly by transposon mutagenesis and knockout techniques, and the surfactin yield of the derivative H5 (△GltB) was increased approximately 7-folds, reaching to 1.48 g/L. The molecular mechanism of high yielding surfactin in △GltB was investigated by the transcriptomic and KEGG pathway analysis. The results indicated that △GltB enhanced its ability to synthesize surfactin mainly by promoting transcription of the srfA gene cluster and inhibiting degradation of some key precursors such as fatty acid. Secondly, we obtained a triple mutant derivative BsC3 by cumulative mutagenesis of the negative genes GltB, RapF, and SerA, and it could increase the surfactin titer by twofold, reaching to 2.98 g/L. Thirdly, we achieved overexpression of two key rate-limiting enzyme genes, YbdT, and srfAD, and the derivative BsC5 which further increased the surfactin titer by 1.3-fold, reaching to 3.79 g/L. Finally, the yield of surfactin by derivatives was significantly increased under the optimal medium, particularly the BsC5 increased the surfactin titer to 8.37 g/L. To the best of our knowledge, this is one of the highest yields that have been reported. Our work may pave way for large scale production of surfactin by B. velezensis Bs916. Key points: • Elucidation of the molecular mechanism of surfactin high-yielding transposon mutant. • Genetically engineering of B. velezensis Bs916 surfactin titer to 8.37 g/L for large scale preparation. [ABSTRACT FROM AUTHOR]

Climate change and anthropogenic exploitation have led to the gradual salinization of inland waters worldwide. However, the impacts of this process on the prokaryotic plankton communities and their role in biogeochemical cycles in the inland lake are poorly known. Here, we take a space-for-time substitution approach, using 16S rRNA gene amplicon sequencing and metagenomic sequencing. We analyzed the prokaryotic plankton communities of 11 lakes in northwest China, with average water salinities ranging from 0.002 to 14.370%. The results demonstrated that, among the various environmental parameters, salinity was the most important driver of prokaryotic plankton β-diversity (Mantel test, r = 0.53, P < 0.001). (1) Under low salinity, prokaryotic planktons were assembled by stochastic processes and employed diverse halotolerant strategies, including the synthesis and uptake of compatible solutes and extrusion of Na+ or Li+ in exchange for H+. Under elevated salinity pressure, strong homogeneous selection meant that only planktonic prokaryotes showing an energetically favorable halotolerant strategy employing an Mnh-type Na+/H+ antiporter remained. (2) The decreasing taxonomic diversity caused by intense environmental filtering in high-salinity lakes impaired functional diversity related to substance metabolism. The prokaryotes enhanced the TCA cycle, carbon fixation, and low-energy-consumption amino acid biosynthesis in high-salinity lakes. (3) Elevated salinity pressure decreased the negative:positive cohesion and the modularity of the molecular ecology networks for the planktonic prokaryotes, indicating a precarious microbial network. Our findings provide new insights into plankton ecology and are helpful for the protecting of the biodiversity and function of inland lakes against the background of salinization. Key points: • Increased salinity enhances homogeneous selection in the microbial assembly. • Elevated salinity decreases the microbial co-occurrence networks stability. • High salinity damages the microbial function diversity. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of salivary histatin 5 (Hst5) on Porphyromonas gingivalis (P. gingivalis) biofilms in vitro and in vivo and the possible mechanisms. In in vitro experiments, P. gingivalis biomass was determined by crystal violet staining. Polymerase chain reaction, scanning electron microscopy, and confocal laser scanning microscopy were used to determine the Hst5 concentration. A search for potential targets was performed using transcriptomic and proteomic analyses. In vivo experimental periodontitis was established in rats to evaluate the effects of Hst5 on periodontal tissues. Experimental results showed that 25 µg/mL Hst5 effectively inhibited biofilm formation, and increased concentrations of Hst5 increased the inhibitive effect. Hst5 might bind to the outer membrane protein RagAB. A combination of transcriptomic and proteomic analyses revealed that Hst5 could regulate membrane function and metabolic processes in P. gingivalis, in which RpoD and FeoB proteins were involved. In the rat periodontitis model, alveolar bone resorption and inflammation levels in periodontal tissues were reduced by 100 µg/mL Hst5. This study showed that 25 µg/mL Hst5 inhibited P. gingivalis biofilm formation in vitro by changing membrane function and metabolic process, and RpoD and FeoB proteins might play important roles in this process. Moreover, 100 µg/mL Hst5 inhibited periodontal inflammation and alveolar bone loss in rat periodontitis via its antibacterial and anti-inflammatory effects. Key points: • Anti-biofilm activity of histatin 5 on Porphyromonas gingivalis was investigated. • Histatin 5 inhibited Porphyromonas gingivalis biofilm formation. • Histatin 5 showed inhibitory effects on the occurrence of rat periodontitis. [ABSTRACT FROM AUTHOR]

Canine parvovirus (CPV) is an acute and highly infectious virus causing disease in puppies and, thus, affecting the global dog industry. The current CPV detection methods are limited by their sensitivity and specificity. Hence, the current study sought to develop a rapid, sensitive, simple, and accurate immunochromatographic (ICS) test to detect and control the spread and prevalence of CPV infection. More specifically, 6A8, a monoclonal antibody (mAb) with high specificity and sensitivity, was obtained by preliminary screening. The 6A8 antibody was labelled with colloidal gold particles. Subsequently, 6A8 and goat anti-mouse antibodies were coated onto a nitrocellulose membrane (NC) as the test and control lines, respectively. Furthermore, 6A8 and rabbit IgG antibodies were labelled with fluorescent microspheres and evenly sprayed onto a glass fibre membrane. Both strips could be prepared in 15 min with no noticeable cross-reactivity with other common canine intestinal pathogens. The strips were simultaneously used to detect CPV in 60 clinical samples using real-time quantitative PCR, hemagglutination, and hemagglutination inhibition assays. The colloidal gold (fluorescent) ICS test strip was stable for 6 (7) and 4 (5) months at 4 °C and room temperature (18–25 °C). Both test strips were easy to prepare and rapidly detected CPV with high sensitivity and specificity. Moreover, the results were easily interpretable. This study establishes a simple method for two CPV diseases, colloidal gold and fluorescent immunochromatographic (ICS) test strips. Key points: • CPV test strips do not exhibit cross-reactivity with other canine intestinal pathogens. • The strips are stable for months at 4 °C and at room temperature (18–25 °C). • These strips are a promising approach for the timely diagnosis and treatment of CPV. [ABSTRACT FROM AUTHOR]

Insulin-like growth factor-1 (IGF-1) is a pleiotropic protein hormone and has become an attractive therapeutic target because of its multiple roles in various physiological processes, including growth, development, and metabolism. However, its production is hindered by low heterogenous protein expression levels in various expression systems and hard to meet the needs of clinical and scientific research. Here, we report that human IGF-1 and its analog Long R3 IGF-1 (LR3 IGF-1) are recombinant expressed and produced in the Pichia pastoris (P. pastoris) expression system through being fused with highly expressed xylanase XynCDBFV. Furthermore, purified IGF-1 and LR3 IGF-1 display excellent bioactivity of cell proliferation compared to the standard IGF-1. Moreover, higher heterologous expression levels of the fusion proteins XynCDBFV-IGF-1 and XynCDBFV-LR3 IGF-1 are achieved by fermentation in a 15-L bioreactor, reaching up to about 0.5 g/L XynCDBFV-IGF-1 and 1 g/L XynCDBFV-TEV-LR3 IGF-1. Taken together, high recombinant expression of bioactive IGF-1 and LR3 IGF-1 is acquired with the assistance of xylanase as a fusion partner in P. pastoris, which could be used for both clinical and scientific applications. Key points: • Human IGF-1 and LR3 IGF-1 are produced in the P. pastoris expression system. • Purified IGF-1 and LR3 IGF-1 show bioactivity comparable to the standard IGF-1. • High heterologous expression of IGF-1 and LR3 IGF-1 is achieved by fermentation in a bioreactor. [ABSTRACT FROM AUTHOR]

The filamentous fungus Penicillium oxalicum secretes integrative plant polysaccharide-degrading enzymes (PPDEs) applicable to biotechnology. Glycogen synthase kinase-3β (GSK-3β) mediates various cellular processes in eukaryotic cells, but the regulatory mechanisms of PPDE biosynthesis in filamentous fungi remain poorly understood. In this study, POGSK-3β (POX_c04478), a homolog of GSK-3β in P. oxalicum, was characterised using biochemical, microbiological and omics approaches. Knockdown of POGSK-3β in P. oxalicum using a copper-responsive promoter replacement system led to 53.5 − 63.6%, 79.0 − 92.8% and 76.8 − 94.7% decreases in the production of filter paper cellulase, soluble starch-degrading enzyme and raw starch-degrading enzyme, respectively, compared with the parental strain ΔKu70. POGSK-3β promoted mycelial growth and conidiation. Transcriptomic profiling and real-time quantitative reverse transcription PCR analyses revealed that POGSK-3β dynamically regulated the expression of genes encoding major PPDEs, as well as fungal development-associated genes. The results broadened our understanding of the regulatory functions of GKS-3β and provided a promising target for genetic engineering to improve PPDE production in filamentous fungi. Key points: • The roles of glycogen synthase kinase-3β were investigated in P. oxalicum. • POGSK-3β regulated PPDE production, mycelial growth and conidiation. • POGSK-3β controlled the expression of major PPDE genes and regulatory genes. [ABSTRACT FROM AUTHOR]

The p30 protein is abundantly expressed in the early stage of African swine fever virus (ASFV) infection. Thus, it is an ideal antigen candidate for serodiagnosis with the use of an immunoassay. In this study, a chemiluminescent magnetic microparticle immunoassay (CMIA) was developed for the detection of antibodies (Abs) against ASFV p30 protein in porcine serum. Purified p30 protein was coupled to magnetic beads, and the experimental conditions including concentration, temperature, incubation time, dilution ratio, buffers, and other relevant variables were evaluated and optimized. To evaluate the performance of the assay, a total of 178 pig serum samples (117 negative and 61 positive samples) were tested. According to receiver operator characteristic curve analysis, the cut-off value of the CMIA was 104,315 (area under the curve, 0.998; Youden's index, 0.974; 95% confidence interval: 99.45 to 100%). Sensitivity results showed that the dilution ratio of p30 Abs in ASFV-positive sera detected by the CMIA is much higher when compared to commercial blocking ELISA kit. Specificity testing showed that no cross-reactivity was observed with sera positive for other porcine disease viruses. The intraassay coefficient of variation (CV) was < 5%, and the interassay CV was < 10%. The p30-magnetic beads could be stored at 4 °C for more than 15 months without loss of activity. The kappa coefficient between CMIA and INGENASA blocking ELISA kit was 0.946, showing strong agreement. In conclusion, our method showed superiority with high sensitivity, specificity, reproducibility, and stability and potentialized its application in the development of a diagnostic kit for the detection of ASF in clinical samples. Key points: • ASFV tag-free p30 was successfully purified. • High sensitivity, specificity, relatively simple, and time-saving to detect antibody against ASFV were developed. • The development of CMIA will help the clinical diagnosis of ASFV and will be useful for large-scale serological test. [ABSTRACT FROM AUTHOR]

Carbon sources and their utilization are vital for fungal growth and development. C4-dicarboxylic acids are important carbon and energy sources that function as intermediate products of the tricarboxylic acid cycle. Transport and regulation of C4-dicarboxylic acid uptake are mainly dependent on tetracarboxylic acid transporters (Dcts) in many microbes, although the roles of Dct genes in fungi have only been partially characterized. Here, we report on the functions of two Dct genes (Dct1 and Dct2) in the entomopathogenic fungus Metarhizium acridum. Our data showed that loss of the MaDct1 gene affected utilization of tetracarboxylic acids and other carbon sources. ΔMaDct1 mutants showed larger colony sizes with extensive mycelial growth but were delayed in conidiation with decreased conidia yield as compared to the wild-type parental strain. On the nutrient-deficient medium, SYA, the wild-type strain produced microcycle conidia, whereas the ΔMaDct1 mutant produced (normal) aerial conidia. In addition, ΔMaDct1 had decreased tolerance to cell wall perturbing agents, but increased tolerances to UV-B radiation and osmotic stress. Insect bioassays indicated that loss of MaDct1 did not affect pathogenicity. In contrast, no distinct phenotypic change was observed for the MaDct2 mutant in terms of growth and biocontrol characteristics. Transcriptomic profiling between wild type and ΔMaDct1 showed that differentially expressed genes were enriched in carbohydrate and amino acid metabolism, transport and catabolism, and signal transduction. These results demonstrate that MaDct1 regulates the conidiation pattern shift and mycelial growth by affecting utilization of carbon sources. These findings are helpful for better understanding the effect of intermediates of carbon metabolism on fungal growth and conidiation. Key points: • MaDct1 influences fungal growth and conidiation by affecting carbon source utilization. • MaDct1 regulates conidiation pattern shift under nutrient deficiency condition. • MaDct1 is involved in stress tolerance and has no effect on virulence. • MaDct2 has no effect on growth and biocontrol characteristic. [ABSTRACT FROM AUTHOR]

The γ-glutamyl tripeptide glutathione (γ-Glu-Cys-Gly) is a low molecular thiol that acts as antioxidant in response to oxidative stress in eukaryotes and prokaryotes. γ-Glutamyl dipeptides including γ-Glu-Cys, γ-Glu-Glu, and γ-Glu-Gly also have kokumi activity. Glutathione is synthesized by first ligating Glu with Cys by γ-glutamylcysteine ligase (Gcl/GshA), and then the resulting dipeptide γ-glutamylcysteine is ligated with Gly by glutathione synthetase (Gs/GshB). GshAB/GshF enzymes that contain both Gcl and Gs domains are capable of catalyzing both reactions. The current study aimed to characterize GshAB from Tetragenococcus halophilus after heterologous expression in Escherichia coli. The optimal conditions for GshAB from T. halophilus were pH 8.0 and 25 °C. The substrate specificity of the Gcl reaction of GshAB was also determined. GshAB has a high affinity to Cys. γ-Glu-Cys was the only dipeptide generated when Glu, Cys, Gly, and other amino acids were present in the reaction system. This specificity differentiates GshAB from T. halophilus from Gcl of heterofermentative lactobacilli and GshAB of Streptococcus agalactiae, which also use amino acids other than Cys as glutamyl-acceptor. Quantification of gshAB in cDNA libraries from T. halophilus revealed that gshAB was overexpressed in response to oxidative stress but not in response to acid, osmotic, or cold stress. In conclusion, GshAB in T. halophilus served as part of the oxidative stress response but this study did not provide any evidence for a contribution to the resistance to other stressors. Key points Glutathione synthesis in Tetragenococcus halophilus is carried out by the two-domain enzyme GshAB. GshAB is inhibited by glutathione and is highly specific for Cys as acceptor. T. halophilus synthesizes glutathione in response to oxidative stress. [ABSTRACT FROM AUTHOR]

Protein purification is a basic technology in both biological research and industrial production, and efficient, convenient, economical, and environmentally friendly purification methods have always been pursued. In this study, it was found that alkaline earth metal cations (Mg2+, Ca2+) and alkali metal cations (Li+, Na+, K+) and even nonmetal cations (e.g., NH4+, imidazole, guanidine, arginine, lysine) can precipitate multi-histidine-tagged proteins (at least two tags in a whole protein) at low salts concentrations that are 1–3 orders of magnitude lower than salting-out, and precipitated proteins could be dissolved at moderate concentration of corresponding cation. Based on this finding, a novel cation affinity purification method was developed, which requires only three centrifugal separations to obtain highly purified protein with purification fold similar to that of immobilized metal affinity chromatography. The study also provides a possible explanation for unexpected protein precipitation and reminds researchers to consider the influence of cations on the experimental results. The interaction between histidine-tagged proteins and cations may also have broad application prospects. Key points: • Histidine-tagged proteins can be precipitated by low-concentrations common cations • A novel nonchromatographic protein purification method was developed • Purified protein can be obtained in pellet form by only three centrifugations [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is the second most common neurodegenerative disease but still lacks a preclinical strategy to identify it. The diagnostic value of intestinal mucosal α-synuclein (αSyn) in PD has not drawn a uniform conclusion. The relationship between the alteration of intestinal mucosal αSyn expression and mucosal microbiota is unclear. Nineteen PD patients and twenty-two healthy controls were enrolled in our study from whom were collected, using gastrointestinal endoscopes, duodenal and sigmoid mucosal samples for biopsy. Multiplex immunohistochemistry was performed to detect total, phosphorylate, and oligomer α-synuclein. Next-generation 16S rRNA amplicon sequencing was applied for taxonomic analysis. The results implied that oligomer α-synuclein (OSyn) in sigmoid mucosa of PD patients was transferred from the intestinal epithelial cell membrane to the cytoplasm, acinar lumen, and stroma. Its distribution feature was significantly different between the two groups, especially the ratio of OSyn/αSyn. The microbiota composition in mucosa also differed. The relative abundances of Kiloniellales, Flavobacteriaceae, and CAG56 were lower, while those of Proteobacteria, Gammaproteobacteria, Burkholderiales, Burkholdriaceae, Oxalobacteraceae, Ralstonia, Massilla, and Lactoccus were higher in duodenal mucosa of PD patients. The relative abundances of Thermoactinomycetales and Thermoactinomycetaceae were lower, while those of Prevotellaceae and Bifidobacterium longum were higher in patients' sigmoid mucosa. Further, the OSyn/αSyn level was positively correlated with the relative abundances of Proteobacteria, Gammaproteobacteria, Burkholderiales, Pseudomonadales, Burkholderiaceae, and Ralstonia in the duodenal mucosa, while it was negatively correlated with the Chao1 index and observed operational taxonomic units of microbiota in sigmoid mucosa. The intestinal mucosal microbiota composition of PD patients altered with the relative abundances of proinflammatory bacteria in the duodenal mucosa increased. The ratio of the OSyn/αSyn level in the sigmoid mucosa indicated a potential diagnostic value for PD, which also correlated with mucosal microbiota diversity and composition. Key points: • The distribution of OSyn in sigmoid mucosa differed between PD patients and healthy controls. • Significant alterations in the microbiome were found in PD patients' gut mucosa. • OSyn/αSyn level in sigmoid mucosa indicated a potential diagnostic value for PD. [ABSTRACT FROM AUTHOR]

Chinese Baijiu, the national liquor of China, is also one of the world-renowned distilled spirits. Jiuqu, a fermentation starter, is the masterpiece of traditional food biotechnology with a long history in China. Compared to western brewing technology of using malt and yeast in stages, the mode of using jiuqu (or combined with pit mud, a activated sludge) for Baijiu brewing is recognized in China. So far, culture-dependent, molecular biology technology and omics approaches have provided deeper insights into study the jiuqu microbiome. Jiuqu is considered to be a microecosystem with diverse and unique microorganisms, in which fascinating features of saccharification, alcohol fermentation, and flavors generation appear. However, knowledge about microbial diversity of jiuqu and their roles involved in Baijiu fermentation is still fragmentary and not systematic enough. Therefore, this review introduced and compared three basic types of jiuqu starter: daqu, xiaoqu and fuqu. We described in detail the microbial succession during preparation of jiuqu, aiming to emphasize that succession process promotes to formation of its stable distribution of microbial community. We also summarized the main species originated from jiuqu and their various properties. Furthermore, reported results about fermentation features of saccharification, alcohol fermentation, and flavors generation in jiuqu microbiome were generalized, and these features were emphasized to play the potential role in Baijiu brewing. Although the current work is limited, promising clues can be traced for future investigation on comprehensive metabolic processes in jiuqu. Key points: • The various microorganisms present in jiuqu, and each has its specific property. • Microbial succession in preparation promotes to distribution of microbial community. • Jiuqu contributes the potential of saccharification, fermentation and flavors generation to Baijiu brewing. [ABSTRACT FROM AUTHOR]

Lignocellulosic biomass is considered the most abundant and renewable feedstock for biobased butyric acid production. However, the furan derivatives (FAs, mainly furfural and 5-hydroxymethylfurfural) generated from the pretreatment of lignocellulose severely inhibit the growth of Clostridium tyrobutyricum, which is the best strain for producing butyric acid. The tolerance mechanism of C. tyrobutyricum to FAs has not been investigated thus far. Here, the response of C. tyrobutyricum ATCC 25755 to FA challenge was first evaluated by using comprehensive transcriptional analysis. The results indicated that the genes related to membrane transport, heat shock proteins, and transcriptional regulation were upregulated under FA stress. However, the expression of almost all genes encoding reductases was not changed, and only the ad gene CTK_RS02625 and the bud gene CTK_RS07810 showed a significant increase of ~ 1.05-fold. Then, the enzyme activity assays indicated that BUD could catalyze the reduction of FAs with relatively low activity and that AD could not participate in the conversion of FAs, indicating that the inability to rapidly convert FAs to their low-toxicity alcohols may be the main reason for the low FA tolerance of C. tyrobutyricum. This research provides insights into the development of FA-tolerant strains, thereby enhancing the bioconversion of lignocellulosic biomass to butyric acid. Key points: • The response of C. tyrobutyricum to FAs was evaluated for the first time. • Genes encoding membrane transporters and heat shock proteins were triggered by FAs. • A lack of effective FA reductases leads to low FA tolerance in C. tyrobutyricum. [ABSTRACT FROM AUTHOR]

A high production mutated strain Bacillus thuringiensis X023PN (BtX023PN) was screened from the wild strain Bacillus thuringiensis X023 (BtX023) after atmospheric and room temperature plasma (ARTP) and nitrosoguanidine (NTG) mutation. BtX023PN grows faster than the wild strain, and its lysis of mother cell was 6 h ahead BtX023, but the ability of sporulation was significantly reduced. Bioassay indicated that compared with the wild type strain, the virulence of BtX023PN against Plutella xylostella (P. xylostella) and Mythimna seperata (M. seperata) increased to 2.33-fold and 2.13-fold respectively. qRT-PCR and SDS-PAGE demonstrated that the production of Cry1Ac increased by 61%. Resequence indicated that the mutated sites enriched on the key carbohydrate metabolism and amino acid metabolism. This study provides a new strain resource for the development of Bt insecticides and a feasible technical strategy for the breeding of Bt. Key points: • Atmospheric and room temperature plasma used in breeding of Bacillus thuringiensis. • Less stationary phase time with more ICP production. • Semi-lethal concentration against Plutella xylostella reduced by about 57% [ABSTRACT FROM AUTHOR]

Tetragenococcus halophilus is a moderately halophilic lactic acid bacterium widely used in high-salt food fermentation because of its coping ability under various stress conditions. Bacterial toxin–antitoxin (TA) modules are widely distributed and play important roles in stress response, but those specific for genus Tetragenococcus have never been explored. Here, a bona fide TA module named DinJ1-YafQ1tha was characterized in T. halophilus. The toxin protein YafQ1tha acts as a ribonuclease, and its overexpression severely inhibits Escherichia coli growth. These toxic effects can be eliminated by introducing DinJ1tha, indicating that YafQ1tha activity is blocked by the formed DinJ1-YafQ1tha complex. In vivo and in vitro assays showed that DinJ1tha alone or DinJ1-YafQ1tha complex can repress the transcription of dinJ1-yafQ1tha operon by binding directly to the promoter sequence. In addition, dinJ1-yafQ1tha is involved in plasmid maintenance and stress response, and its transcriptional level is regulated by various stresses. These findings reveal the possible roles of DinJ1-YafQ1tha system in the stress adaptation processes of T. halophilus during fermentation. A single antitoxin DinJ2tha without a cognate toxin protein was also found. Its sequence shows low similarity to that of DinJ1tha, indicating that this antitoxin may have evolved from a different ancestor. Moreover, DinJ2tha can cross-interact with noncognate toxin YafQ1tha and cross-regulate with dinJ1-yafQ1tha operon. In summary, DinJ-YafQtha characterization may be helpful in investigating the key roles of TA systems in T. halophilus and serves as a foundation for further research. Key points: • dinJ1-yafQ1thais the first functional TA module characterized in T. halophilus and upregulated significantly upon osmotic and acidic stress. • DinJ2thacan exhibit physical and transcriptional interplay with DinJ1-YafQ1tha. • dinJ2thamay be acquired from bacteria in distant affiliation and inserted into the T. halophilus genome through horizontal gene transfer. [ABSTRACT FROM AUTHOR]

In the present study, the complete mitogenome of Turbinellus floccosus was sequenced, assembled, and compared with other basidiomycete mitogenomes. The mitogenome of T. floccosus consists of a circular DNA molecule, with a size of 62,846 bp. Gene arrangement analysis indicated that large-scale gene rearrangements occurred in the levels of family and genus of basidiomycete species, and the mitogenome of T. floccosus contained a unique gene order. A significant correlation between the number of introns and the mitochondrial genome size of Basidiomycota were detected (P < 0.01). A total of 896 introns were detected in the core protein-coding genes (PCGs) of 74 basidiomycete species, and the cox1 gene was the largest host gene of basidiomycete introns. Intron position class (Pcls) P383 in the cox1 gene was the most common intron in Basidiomycota, which distributed in 40 of 74 basidiomycete species. In addition, frequent intron loss/gain events were detected in basidiomycete species. More than 50% of bases around insertion sites (− 15 bp to 15 bp) of Pcls from different species were conservative, indicating site preferences of intron insertions in Basidiomycota. Further analysis showed that 76.09% of introns tended to insert downstream to a T base in Basidiomycota. Phylogenetic analysis for 74 basidiomycetes indicated mitochondrial genes are effective molecular markers for phylogeny of basidiomycetes. The study served as the first report on the mitogenome from the family Gomphaceae, which will help to understand the intron origin and evolution in Basidiomycota. Key points: • The mitogenome of Turbinellus floccosus had a unique gene arrangement. • Intron loss/gain events were detected in the 74 basidiomycete species. • Introns tend to insert downstream of a T base in basidiomycete mitogenomes. [ABSTRACT FROM AUTHOR]

Constructing bionic extracellular matrix (ECM) is an attractive proposition for tissue engineering and clinical regeneration therapy involving the stemness of stem cells. Here, a novel recombinant protein fibronectin-collagen peptide (FCP) was designed to modulate the function of ECM expressed by Picha. pastoris strain X33. This FCP promotes cell migration and adhesion and maintains rBMSC stemness by binding integrin β3. Its effects were blocked by both integrin β3 siRNA and the integrin β3 inhibitor Cilengitide. A template-independent ab initio prediction modeling approach is the best approach to construct a stable FCP protein model, which predicts the binding sites between FCP and integrin β3. FCP may be used in the in vitro culture and clinical regeneration of stem cells that highly express integrin β3, such as hematopoietic stem cells. The study provides information on the molecular structure of FCP and its bioactivity, which can be used to design new compounds. Key points: • Design a novel recombinant fibronectin-collagen peptide biomimetic ECM. • FCP promotes cell adhesion, migration, and proliferation. • Predicted and verified FCP structure and affinity with integrin β3. • FCP binds integrin β3 to maintain rBMSC stemness. [ABSTRACT FROM AUTHOR]

Artemisinin is a component part of current frontline medicines for the treatment of malaria. The aim of this study is to make analogues of artemisinin using microbial transformation and evaluate their in vitro antimalarial activity. A panel of microorganisms were screened for biotransformation of artemisinin (1). The biotransformation products were extracted, purified and isolated using silica gel column chromatography and semi-preparative HPLC. Spectroscopic methods including LC-HRMS, GC–MS, FT-IR, 1D and 2D NMR were used to elucidate the structure of the artemisinin metabolites.1H NMR spectroscopy was further used to study the time-course biotransformation. The antiplasmodial activity (IC50) of the biotransformation products of 1 against intraerythrocytic cultures of Plasmodium falciparum were determined using bioluminescence assays. A filamentous fungus Aspergillus niger CICC 2487 was found to possess the best efficiency to convert artemisinin (1) to a novel derivative, 4-methoxy-9,10-dimethyloctahydrofuro-(3,2-i)-isochromen-11(4H)-one (2) via ring rearrangement and further degradation, along with three known derivatives, compound (3), deoxyartemisinin (4) and 3-hydroxy-deoxyartemisinin (5). Kinetic study of the biotransformation of artemisinin indicated the formation of artemisinin G as a key intermediate which could be hydrolyzed and methylated to form the new compound 2. Our study shows that the anti-plasmodial potency of compounds 2, 3, 4 and 5 were ablated compared to 1, which attributed to the loss of the unique peroxide bridge in artemisinin (1). This is the first report of microbial degradation and ring rearrangement of artemisinin with subsequent hydrolysis and methoxylation by A.niger. Key points: • Aspergillus niger CICC 2487 was found to be efficient for biotransformation of artemisinin • A novel and unusual artemisinin derivative was isolated and elucidated • The peroxide bridge in artemisinin is crucial for its high antimalarial potency • The pathway of biotransformation involves the formation of artemisinin G as a key intermediate [ABSTRACT FROM AUTHOR]

Rhodococcus pyridinivorans B403 is a promising bacterium for degrading phenolic pollutants. In the application, the high-concentration substrate has a significant inhibitory effect on cell growth and phenol degradation, which makes adaptive evolution study of bacteria an important guarantee for further application. The present work found evolved R. pyridinivorans (X1 and X2) had enhanced tolerance to phenolic pollutants as compared to the ancestor strain: the minimum inhibitory concentrations (MIC) of phenol, m-cresol, and catechol increased from 1.2, 0.7, 0.8 g/L to 1.8, 1.0, 1.2 g/L of strain X1, and to 2.4, 1.2, 1.4 g/L of strain X2, respectively. Furthermore, compared to B403, X1, and X2 accumulated more biomass in 500-mg/L cresol medium and degraded phenols more efficiently. Correspondingly, genome sequencing revealed that the mutation sites in genes were annotated as encoding phosphotransferase, MFS transporter, AcrR regulator, and GlpD regulator in the adapted strains, which were closely associated with improved phenol tolerance and degradation. The conclusions provided theoretical basis for the phenol tolerance and degradation, which could promote construction of engineering bacteria for practical application. Key points: • Evolved strains were more resistant to phenols • Evolved strains degraded phenols more quickly • Genome sequencing elucidated mechanisms of enhanced phenol tolerance and degradation [ABSTRACT FROM AUTHOR]

Nitriles derived from glucosinolates (GSLs) in rapeseed meal (RSM) can cause lesions on animal liver and kidneys. Nitrilase converts nitriles to carboxylic acids and NH3, eliminating their toxicity. Here we describe a nitrilase, BnNIT2, from Brassica napus (optimal temperature, 45 °C; pH, 7.0) that is stable at 40 °C and has a wide substrate specificity. Recombinant BnNIT2 converted the three main nitriles from GSLs (3-hydroxy-4-pentenenitrile, 3-butenenitrile, and 4-pentenenitrile), with the highest specific activity (58.6 U/mg) for 4-pentenenitrile. We used mutagenesis to improve the thermostability of BnNIT2; the resulting mutant BnNIT2-H90M had an ~ 14.5% increase in residual activity at 50 °C for 1 h. To verify the functionality of BnNIT2, GSLs were extracted from RSM and converted into nitriles at pH 5.0 in the presence of Fe2+. Then, BnNIT2 was used to degrade the nitriles from GSLs; ultimately, ~ 80% of nitriles were removed. Thus BnNIT2 is a potential enzyme for detoxification of RSM. Key points: • Functional identification of the plant nitrilase BnNIT2. • Identified a mutant, H90M, with improved thermostability. • BnNIT2 was capable of degrading nitriles from transformed GSLs. [ABSTRACT FROM AUTHOR]

Intestinal microbiota play an important role in the intestinal immunity and nutrient absorption, even muscle nutritional components, and the composition and function were affected by environment. In this study, the intestinal microbiota and immune enzyme, nutritional flavor of muscle of crayfish in rice field, and pond cultivation model were compared in summer and autumn. The results of Shannon diversity and Chao 1 index of intestinal microbiota based on 16S sequencing analysis showed that the diversity and abundance in autumn were higher than in summer. And the diversity and abundance of intestinal microbiota of different model in the same season were different. Four dominant phyla (relative abundance > 5% at least in one sample) of the intestinal microbiota were Bacteroidetes, Firmicutes, Proteobacteria, and Tenericutes. From summer to autumn, the intestinal immune enzyme activity of crayfish in both models showed a decreasing trend. In summer, the activity of catalase and alkaline phosphatase of crayfish cultured in the pond was significantly higher than that in rice field (P < 0.05). In autumn, the activity of catalase and lysozyme of crayfish cultured in rice field was significantly higher than that in pond (P < 0.05). The contents of umami and sweetish amino acids of muscle were higher in rice field than in pond, and the percentage of glutamic acid and alanine was significantly higher in rice field than in pond (P < 0.05). Thus, rice field model can make crayfish a more stable intestinal environment and a better intestinal immune enzyme activity and muscular flavor. Key points • The intestinal microbiota of crayfish in rice field had tended to stabilize from summer to autumn. • The crayfish had better nutrient absorption and stronger immune abilities in the rice field. • The crayfish cultured in rice field had higher overall umami concentration than in pond. [ABSTRACT FROM AUTHOR]

The halophilic lactic acid bacterium Tetragenococcus halophilus has been widely used in high-salinity fermentation processes of food. Previous studies have indicated that the catabolism of arginine may contribute to the osmotic stress adaptation of T. halophilus. Unusually, in the chromosome of T. halophilus, preceding the arginine deiminase (ADI) operon, locate two co-transcribed genes, both encoding an ArgR regulator; similar structure was rarely found and the roles of the regulators have not been demonstrated. In the current study, regulatory roles of these two nonidentical ArgR regulators on the arginine metabolism of T. halophilus were investigated. The results show that these two regulators play different roles in arginine metabolism, ArgR1 acts as a negative regulator of the ADI pathway by binding to the promoter sequences and repressing the transcription of genes, and the addition of arginine or hyper-osmotic stress conditions can abolish the ArgR1 repression, whereas ArgR2 negatively regulates the genes involved in arginine biosynthesis. Our study found that despite the commonly known roles of the ArgR regulators as the activator of arginine catabolism and the repressor of arginine biosynthesis, which are found in most studied bacteria possessed one ArgR regulator, the two nonidentical ArgR regulators of T. halophilus both act as repressors, and the repression by which is regulated when sensing changes of environments. By revealing the regulation of arginine metabolism, the current study provides molecular insights and potential tools for future applications of halophiles in biotechnology. Key points: • The expression of the ADI pathway of T. halophilus is regulated by carbon sources and osmotic stress. • The arginine metabolism process of T. halophilus is fine-tuned by the two ArgR regulators. • The ADI pathway may contribute to the osmotic stress adaptation by generating more energy and accumulating citrulline which acts as compatible solute. [ABSTRACT FROM AUTHOR]

African swine fever virus (ASFV) causes acute, febrile, and highly contagious diseases in swine. Early diagnosis is critically important for African swine fever (ASF) prevention and control in the absence of an effective vaccine. P30 is one of the most immunogenic proteins that are produced during the early stage of an ASFV infection. This makes P30 a good serological target for ASF detection and surveillance. In this study, two P30-reactive monoclonal antibodies (mAbs), 2H2 and 5E8, were generated from mice immunized with recombinant P30 protein (rP30). Epitope mapping was performed with overlapping polypeptides, alanine mutants, and synthetic peptides. The mapping results revealed that 2H2 recognized a region located in the N-terminal, 16–48 aa. In contrast, 5E8 recognized a linear epitope in the C-terminal, 122–128 aa. Further analysis indicated that the epitope recognized by 2H2 was highly conserved in genotypes I and II, while the 5E8 epitope was conserved in most genotypes and the Ser to Pro change at position 128 in genotypes IV, V, and VI did not affect recognition. Overall, the results of this study provide valuable information on the antigenic regions of ASFV P30 and lay the foundation for the serological diagnosis of ASF and vaccine research. Key points: • Two specific and reactive mAbs were prepared and their epitopes were identified. • 2H2 recognized a novel epitope highly conserved in genotypes I and II. • 5E8 recognized a seven-amino acid linear epitope highly conserved in most genotypes. [ABSTRACT FROM AUTHOR]

Aeromonas hydrophila is a zoonotic pathogen that exhibits high level resistance to classic antibiotics and is a heavy burden for aquaculture industry. Lytic enzymes encoded by phages or prophages have shown potential for use against pathogenic bacteria. In this study, an intact prophage (named phAhD4) was identified from A. hydrophila D4. phAhD4 is highly conserved in all 10 published A. hydrophila sequence type (ST) 251 strains and is unique to the ST251 strains. The unique endolysin PlyD4, encoded by phAhD4, was obtained by prokaryotic expression. PlyD4 showed bactericidal activity against a broad range of bacterial species in vitro, including A. hydrophila, Aeromonas veronii, Vibrio parahemolyticus, Pseudomonas aeruginosa, and so on. Synergistically with 5 mmol/L ethylene diamine tetraacetic acid (EDTA), the ratio of the optical density at 600 nm (OD600) of PlyD4 treatment versus the OD600 with no PlyD4 treatment for most tested strains decreased from 1 to 0.1–0.8 within 2 h. PlyD4 exhibited optimal activity at 28 °C and maintained high activity over a wide pH range (pH 6–10). Divalent metal ions conferred significant enhancement to PlyD4 lytic activity at low concentrations (0.1 mmol/L). In vivo, a 4.5 μg dose of PlyD4 protected 75.0% (15/20) of zebrafish in a bacteremia model of A. hydrophila D4 infection. These results indicated that PlyD4 was an effective therapeutic agent against multiple aquaculture-related pathogens. To the best of our knowledge, this study is the first to report on an A. hydrophila prophage endolysin that exerts antibacterial activity against a broad range of pathogens. Key points: • The prophage phAhD4 is highly conserved in 10 published A. hydrophila ST251 strains. • PlyD4 exerts antibacterial activity against multiple aquaculture-related pathogens. • PlyD4 conferred protection against A. hydrophila infection in a zebrafish model. [ABSTRACT FROM AUTHOR]

African swine fever (ASF) is an acute and highly contagious infectious disease caused by the African swine fever virus (ASFV). Currently, there is no vaccine against ASF worldwide, and no effective treatment measures are available. For this reason, developing a simple, rapid, specific, and sensitive serological detection method for ASFV antibodies is crucial for the prevention and control of ASF. In this study, a 1:1 mixture of gold-labeled p30 and p72 probes was used as the gold-labeled antigen. The p30 and p72 proteins and their monoclonal antibodies were coated on a nitrocellulose membrane (NC) as a test (T) line and control (C) line, respectively. A colloidal-gold dual immunochromatography strip (ICS) for ASFV p30 and p72 protein antibodies was established. The results showed that the colloidal-gold dual ICS could specifically detect ASFV antibodies within 5–10 min. There was no cross-reaction after testing healthy pig serum; porcine reproductive and respiratory syndrome virus (PRRSV), foot-and-mouth disease type A virus (FMDV-A), foot-and-mouth disease type O virus (FMDV-O), porcine circovirus type 2 (PCV-2), and classical swine fever virus (CSFV) positive sera. A positive result was obtained only for the positive control P1. The sensitivity of the test strips was 1:256, which was equivalent to that of commercially ELISA kits. Their coincidence rate with the two commercial ASFV ELISA antibodies detection kits was higher than 98%. The test strips were stably stored at 18–25 °C and 4 °C for 4 and 6 months, respectively. The colloidal-gold dual ICS prepared in this study had high sensitivity and specificity and were characterized by rapid detection, simple operation, and easy interpretation of results. Therefore, they are of great significance to diagnose, prevent, and control African swine fever. Key points: • We establish an antibody detection that is quick and can monitor an ASF infection. • We observe changes in two protein antibodies to dynamically monitor ASF infection. • We use diversified detection on a single test strip to detect both antibodies. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) emissions from forest ecosystems originate largely from soil respiration, and microbial heterotrophic respiration plays a critical role in determining organic carbon (C) stock. This study investigated the impacts of successive nitrogen (N) and phosphorus (P) fertilization after 9 years on soil organic C stock; CO2 emission; and microbial biomass, community, and function in a Chinese fir plantation. The annual fertilization rates were (1) CK, control without N or P fertilization; (2) N50, 50 kg N ha−1; (3) N100, 100 kg N ha−1; (4) P50, 50 kg P ha−1; (5) N50P50, 50 kg N ha−1 + 50 kg P ha−1; and (6) N100P50, 100 kg N ha−1 + 50 kg P ha−1. The N100P50 treatment had the highest cumulative soil CO2 emissions, but the CK treatment had the lowest cumulative soil CO2 emissions among all treatments. The declines of soil organic C (SOC) after successive 9-year fertilization were in the order of 100 kg N ha−1 year−1 > 50 kg N ha−1 year−1 > CK. Compared to the CK treatment, successive N fertilization significantly changed soil microbial communities at different application rates and increased the relative gene abundances of glycoside hydrolases, glycosyl transferases, carbohydrate-binding modules, and polysaccharide lyases at 100 kg N ha−1 year−1. Relative to P fertilization alone (50 kg P ha−1 year−1), combined N and P fertilization significantly altered the soil microbial community structure and favored more active soil microbial metabolism. Microbial community and metabolism changes caused by N fertilization could have enhanced CO2 emission from heterotrophic respiration and eventually led to the decrease in organic C stock in the forest plantation soil. Key points: • N fertilization, alone or with P, favored more active microbial metabolism genes. • 100 kg N ha−1 fertilization significantly changed microbial community and function. • N fertilization led to a "domino effect" on the decrease of soil C stock. [ABSTRACT FROM AUTHOR]

A 28-kDa polysaccharide-peptide (PGL) with antidepressant-like activities was isolated from spores of the mushroom Ganoderma lucidum. It was unadsorbed on DEAE-cellulose. Its internal amino acid sequences manifested pronounced similarity with proteins from the mushrooms Lentinula edodes and Agaricus bisporus. The monosaccharides present in 28-kDa PGL comprised predominantly of glucose (over 90%) and much fewer galactose, mannose residues, and other residues. PGL manifested antidepressant-like activities as follows. It enhanced viability and DNA content in corticosterone-injured PC12 cells(a cell line derived from a pheochromocytoma of the rat adrenal medulla with an embryonic origin from the neural crest containing a mixture of neuroblastic cells and eosinophilic cells) and reduced LDH release. A single acute PGL treatment shortened the duration of immobility of mice in both tail suspension and forced swimming tests. PGL treatment enhanced sucrose preference and shortened the duration of immobility in mice exposed to chronic unpredictable mild stress (CUMS). Chronic PGL treatment reversed the decline in mouse brain serotonin and norepinephrine levels but did not affect dopamine levels. PGL decreased serum corticosterone levels and increased BDNF mRNA and protein levels and increased synapsin I and PSD95 levels in the prefrontal cortex. This effect was completely blocked by pretreatment with the BDNF antagonist K252a, indicating that PGL increased synaptic proteins in a BDNF-dependent manner. Key points • An antidepressive polysaccharide-peptide PGL was isolated fromG. lucidumspores. • PGL protected PC12 nerve cells from the toxicity of corticosterone. • PGL upregulated BDNF expression and influenced key factors in the prefrontal cortex. [ABSTRACT FROM AUTHOR]

Chlorogenic acids (CGA), the most abundant natural polyphenol present in human diet and plants, have attracted considerable research interest because of their broad bioactivities including the antimicrobial activity. However, little is known about their influences on intestinal bacterial communities. Here, we described a response in intestinal microbiome to CGA using a porcine model. Twenty-four weaned pigs were allotted to two groups and fed with a basal diet or a basal diet containing 1000 mg/kg CGA. Results showed that CGA significantly increased the length of the small intestine (P < 0.05) and enhanced the activity of diamine oxidase (DAO) and the concentration of MHC-II in the jejunal and ileal mucosa (P < 0.05). Moreover, the acetate concentration in ileum and cecum digesta, and the propionate and butyrate concentrations in the cecum digesta, were significantly elevated by CGA (P < 0.05). Interestingly, CGA significantly increased the total 16S rRNA gene copies and bacterial alpha diversity in the cecum (P < 0.05). The relative abundance of bacteria from phyla Firmicutes and Bacteroidetes was increased in the cecum digesta (P < 0.05), whereas the abundance of bacteria from phylum Protebacteria was decreased by CGA (P < 0.05). Importantly, pigs on CGA-containing diet had higher abundance of Lactobacillus spp., Prevotella spp., Anaerovibrio spp., and Alloprevotella spp. in the cecum (P < 0.05). Not only did our study suggest a synergic response of intestinal barrier function and microbiota to the CGA, but the result will also contribute to understanding of the mechanisms behind the CGA-modulated gut health. [ABSTRACT FROM AUTHOR]

The toxicity of methyl viologen (MV) to organisms is mainly due to the oxidative stress caused by reactive oxygen species produced from cell response. This study mainly investigated the response of Synechocystis sp. PCC 6803 to MV by combining transcriptomic and metabolomic analyses. Through transcriptome sequencing, we found many genes responding to MV stress, and analyzed them by weighted gene co-expression network analysis (WGCNA). Meanwhile, many metabolites were also found by metabolomic analysis to be regulated post MV treatment. Based on the analysis results of Kyoto encyclopedia of genes and genomes (KEGG) of the differentially expressed genes (DEGs) in the transcriptome and the differential metabolites in the metabolome, the dynamic changes of genes and metabolites involved in ten metabolic pathways in response to MV were analyzed. The results indicated that although the oxidative stress caused by MV was the strongest at 6 h, the proportion of the upregulated genes and metabolites involved in these ten metabolic pathways was the highest. Photosynthesis positively regulated the response to MV-induced oxidative stress, and the regulation of environmental information processing was inhibited by MV. Other metabolic pathways played different roles at different times and interacted with each other to respond to MV. This study comprehensively analyzed the response of Synechocystis sp. PCC 6803 to oxidative stress caused by MV from a multi-omics perspective, with providing key data and important information for in-depth analysis of the response of organisms to MV, especially photosynthetic organisms. Key points: • Methyl viologen (MV) treatment caused regulatory changes in genes and metabolites. • Proportion of upregulated genes and metabolites was the highest at 6-h MV treatment. • Photosynthesis and environmental information processing involved in MV response. [ABSTRACT FROM AUTHOR]

Hepatitis E, a significant global public health issue in China, is caused by sporadic infections with regional hepatitis E virus (HEV) genotypes 1, 3, and 4. To date, most immunoassays currently used to test human sera for the presence of anti-HEV antibodies cannot identify HEV at the genotype level. However, such information would be useful for identifying the source of infecting virus. Therefore, here we describe the development of a competitive enzyme-linked immunosorbent assay (ELISA) for detecting anti-genotype 1 HEV antibodies in human sera. Using recombinant genotype 1 HEV ORF3 protein as immunogen, traditional hybridoma technology was employed to generate seven monoclonal antibodies (mAbs), of which two mAbs specifically reacted with the immunogen. One of these two mAbs, 1D2, was labeled with horseradish peroxidase (HRP) for use in competitive ELISA (cELISA). After cELISA optimization using a checkerboard assay design, the amount of ORF3SAR−55 as coating antigen (100 ng/well), HRP-1D2 mAb concentration (1 μg/mL), and test serum dilution (1:10) were selected and a result ≥ 19.5 was used as the cutoff for a positive result. Importantly, cross-genotype cELISA results indicated that the cELISA could not detect anti-genotype 3 rabbit and 4 swine HEV antibodies. Moreover, human sera confirmed as negative for anti-HEV antibodies using the commercial ELISA kit were all negative via cELISA. However, because the commercial ELISA kit detects anti-all genotypes HEV antibodies and the cELISA only detects anti-genotype 1 HEV antibodies, the consistence rate of two assays detecting positive sera is low. In summary, here a cELISA for detecting anti-genotype 1 HEV antibodies was developed for use in epidemiological investigations of genotype 1 HEV infections in humans. Key points: • Seven mAbs were produced using genotype 1 HEV ORF3 protein as immunogen. • One mAb that specifically bound to genotype 1 HEV ORF3 protein was selected and labeled for use in a cELISA to detect anti-genotype 1 HEV antibodies. • The competitive ELISA developed here will aid clinical diagnosis of HEV infections and will be useful for large-scale serological testing of genotype 1 HEV infections in humans. [ABSTRACT FROM AUTHOR]

Temperature is one of the key factors that affects the growth and development of macrofungi. Heat stress not only negatively affects the morphology and growth rate of macrofungi, but also destroys cell structures and influences cell metabolism. Due to loosed structure of cell walls and increased membrane fluidity, which caused by heat stress, the outflow of intracellular nutrients makes macrofungi more vulnerable to invasion by pathogens. Macrofungi accumulate reactive oxygen species (ROS), Ca2+, and nitric oxide (NO) when heat-stressed, which transmit and amplify the heat stimulation signal through intracellular signal transduction pathways. Through regulation of some transcription factors including heat response factors (HSFs), POZCP26 and MYB, macrofungi respond to heat stress by different mechanisms. In this paper, we present mechanisms used by macrofungi to adapt and survive under heat stress conditions, including antioxidant defense systems that eliminate the excess ROS, increase in trehalose levels that prevent enzymes and proteins deformation, and stabilize cell structures and heat shock proteins (HSPs) that repair damaged proteins and synthesis of auxins, which increase the activity of antioxidant enzymes. All of these help macrofungi resist and adapt to heat stress. Key points: • The effects of heat stress on macrofungal growth and development were described. • The respond mechanisms to heat stress in macrofungi were summarized. • The further research directions of heat stress in macrofungi were discussed. [ABSTRACT FROM AUTHOR]

Sucrose phosphorylase (SPase) can specifically catalyze transglycosylation reactions and can be used to enzymatically synthesize α-D-glycosides. However, the low thermostability of SPase has been a bottleneck for its industrial application. In this study, a SPase gene from Leuconostoc mesenteroides ATCC 12,291 (LmSPase) was synthesized with optimized codons and overexpressed successfully in Escherichia coli. A semi-rational design strategy that combined the FireProt (a web server designing thermostable proteins), structure–function analysis, and molecular dynamic simulations was used to improve the thermostability of LmSPase. Finally, one single-point mutation T219L and a combination mutation I31F/T219L/T263L/S360A (Mut4) with improved thermostability were obtained. The half-lives at 50 °C of T219L and Mut4 both increased approximately two-fold compared to that of wild-type LmSPase (WT). Furthermore, the two variants T219L and Mut4 were used to produce α-D-glucosylglycerol (αGG) from sucrose and glycerol by incubating with 40 U/mL crude extracts at 37 °C for 60 h and achieved the product concentration of 193.2 ± 12.9 g/L and 195.8 ± 13.1 g/L, respectively, which were approximately 1.3-fold higher than that of WT (150.4 ± 10.0 g/L). This study provides an effective strategy for improving the thermostability of an industrial enzyme. Key points: • Predicted potential hotspot residues directing the thermostability of LmSPase by semi-rational design • Screened two positive variants with higher thermostability and higher activity • Synthesized α-D-glucosylglycerol to a high level by two screened positive variants [ABSTRACT FROM AUTHOR]

In wild strains of Bacillus, a handful of extracellular natural products act as signals that can regulate multicellular behavior, but relatively little is known about molecular mechanisms' detail. We proposed a previously unreported molecular mechanism for triggering multicellularity in B. velezensis Bs916 by an endogenous cyclic lipopeptide, bacillomycin L. The genome-wide effect on gene expression was caused by the disruption of bacillomycin L gene cluster, and 100 µg/mL bacillomycin L was revealed by quantitative transcriptomics. A total of 878 differentially expressed genes among Bs916, Δbl, and Δbl + 100BL were identified and grouped into 9 functional categories. The transcription levels of 40 candidate genes were further evaluated by RT-qPCR analysis. The expression of eight candidate genes regulated by bacillomycin L in a dose-dependent manner was revealed by LacZ fusion experiment. Although the addition of bacillomycin L could not completely restore the expression levels of the differentially regulated genes in △bl, our results strongly suggest that bacillomycin L acts as a tuning signal of swarming motility and complex biofilm formation by indirectly regulating the expression levels of some two-component systems (TCSs) connector genes, particularly including several Raps that potentially regulate the phosphorylation levels of three major regulators ComA, DegU, and Spo0A. Key points • Proposed model for bacillomycin L regulation in B. velezensis Bs916. • Bacillomycin L can act as an extracellular signal to regulate the phosphorylation levels of three major regulators, ComA, DegU, and Spo0A and control the multicellular processes of vegetative growth, competent, motility, matrix production, sporulation, and autolysis. [ABSTRACT FROM AUTHOR]

Bacteriocins derived from lactic acid bacteria (LAB) are well recognized as promising food preservative due to high safety and potent antibacterial activity against foodborne pathogens and spoilage bacteria. In this study, an antimicrobial agent-producing strain FZU63 from Chinese sauerkraut was identified as Lactobacillus coryniformis based on physio-biochemical characterization and 16S rDNA sequence analysis. In addition, a bacteriocin was purified from the culture supernatant of L. coryniformis FZU63, and its molecular mass was determined as 1493.709 Da. Moreover, the amino acid sequence of the bacteriocin was predicted to be RQQPMTLDYRW-NH2 using nanoliter/microliter liquid chromatography combined with triple quadrupole-linear ion trap tandem mass spectrometry and was named as Lactocin 63. Furthermore, Lactocin 63 displays potent antimicrobial activity against the tested Gram-positive and negative bacteria based on the results of determining MICs. Subsequently, the action mode of Lactocin 63 against Shewanella putrefaciens was investigated. The results demonstrated that Lactocin 63 targets and is adsorbed onto the bacterial cell wall and membrane and then disrupts cytoplasmic membrane, which is leading to leakage of cytoplasm according to the results of flow cytometry analysis and the observation of cellular ultra-structure using confocal laser microscopy and atomic force microscopy. Collectively, these results are helpful and providing the theoretical base for developing and applying LAB-derived bacteriocins as promising bio-preservatives to combat foodborne pathogens and spoilage bacteria in seafood industries. Key points • A bacteriocin-producing strain Lactobacillus coryniformis was isolated. • A novel bacteriocin produced by Lactobacillus coryniformis FZU63 was characterized. • Action mechanism of the bacteriocin against S. putrefaciens was elucidated in vitro. [ABSTRACT FROM AUTHOR]